1. Field of the Invention
The present invention relates to a portable electronic apparatus, known as an integrated circuit card (IC card), which incorporates an IC chip having, e.g., a nonvolatile memory and a control element such as a CPU.
2. Description of the Related Art
A so-called IC card which incorporates an IC chip having, e.g., a nonvolatile memory and a control element such as a CPU has been developed as a portable storage medium. An IC card of this type stores an identification number as key data in its internal memory. When an identification number is externally input, it is collated with the registered identification number stored in the memory, and subsequent memory access is enabled or disabled in accordance with the collation result. In this case, since the identification number in the memory cannot be externally read out, only a person who knows the identification number can access the memory.
As various IC cards have become available, a method of managing a memory in an IC card has been improved. The memory is divided by the concept of a single command data file (first region) accessed in all the applications and a plurality of application data files (second regions) accessed in units of applications. The data files corresponding to the applications are selectively accessed.
However, when corresponding identification numbers are provided in units of application files, as the number of application files is increased, the information indicating whether each of the identification numbers is collated is also increased. For this reason, in a conventional IC card, an identification number common to the common data file and the application data files is merely set. Thus, it is difficult to maintain security as an IC card system.